Acupuncture increasingly is becoming a mainstay of treatment for a number of diseases. Although its acceptance by physicians and scientists in the western world is increasing, reluctance remains strong because its mechanisms of action are poorly defined. This application represents a competitive renewal of our grant to study the neural influence of electroacupuncture (EA) on the autonomic nervous and cardiovascular systems. In the previously funded period we have shown that EA at Neiguan and Zusanli acupoints reduces demand-induced myocardial ischemia by reducing the pressor response during excitatory cardiovascular reflexes. This influence occurs, in part, in the rostral ventral lateral medulla (rVLM) where acupuncture causes prolonged inhibition of premotor sympathoexcitatory neurons that receive convergent input from visceral and somatic nerves. This modulation involves the opioid system, particularly mu- and delta-opioid receptors, suggesting that endorphins and enkephalins are important neurotransmitters. The present grant will extend our prior studies by proposing five mechanistic hypotheses relevant to EA. We will determine: 1) the role of glutamate and its ionotropic NMDA and AMPA excitatory amino acid receptors in rVLM excitatory convergent input during reflex and EA stimulation using pharmacological antagonism; 2) the synaptic location of opioid inhibition of rVLM excitation using both microdialysis and exogenous glutamate to examine pre- and post-synaptic influences; 3) the function of nociceptin and its associated ORL-1 receptor in EA-related modulation of rVLM neuronal activity; 4) using pharmacological and electrophysiological approaches, the transmitter mechanisms of prolonged inhibition of rVLM activity by EA, focusing on opioids, nociceptin and y-aminobutyric acid; and 5) spinal cord dorsal horn delta- and K-opioid and nociceptin ORL-1 mechanisms in segmental and extra-segmental influence of EA on sensory input. These studies will provide important new information about the mechanisms underlying the influence of EA on the autonomic and cardiovascular systems. Much of this knowledge will be applicable clinically. Improved understanding of acupuncture will assist practicing acupuncturists and will provide physicians and scientists with a stronger rationale for using and studying this alternative therapy. [unreadable] [unreadable]